Interlaboratory reproducibility of atypical squamous cells of undetermined significance report: a national survey

The study was aimed at assessing interlaboratory reproducibility in the reporting of cervical smears in the atypical squamous cells of undetermined significance (ASCUS) category. A set of 50 selected slides circulated among 89 laboratories, currently involved in population-based screening programmes for cervical cancer, which provided a diagnostic report according to four main reporting categories based on the 1991 Bethesda system. Interlaboratory agreement was determined according to kappa (K) statistics: overall and weighted K values were determined for each laboratory and for single reporting categories. The results showed a very low reproducibility for the ASCUS category. This finding supports the Bethesda system 1991 recommendation to limit the use of this reporting category and suggests that the clinical response to ASCUS reports should be decided locally, based on the observed positive predictive value for cervical intraepithelial neoplasia 2 or more severe lesions.     

The use of the 'borderline' category in the reporting of cervical cytopathology in the UK: results of a survey conducted under the aegis of the British Society for Clinical Cytology

Objective: To determine how the ‘borderline’ category was used by cytopathologists in the UK when reporting cervical smears. Methods: A questionnaire was sent by email to members of the British Society for Clinical Cytology. Results: There is wide variation in the use of the ‘borderline’ category in the UK but the majority of respondents (77.6%) used it when reporting smears that were either on the borderline between negative and low grade squamous dyskaryosis (‘borderline ?low grade’), or on the borderline between negative and high grade squamous dyskaryosis (‘borderline ?high grade’), or on the borderline between negative and glandular dyskaryosis ‘borderline ?glandular dyskaryosis’). A significant minority (15.7%), however, did not use ‘borderline’ when reporting smears that showed an abnormality that was possibly high grade squamous dyskaryosis. A majority (79.1%) of respondents thought that it would be useful to have separate reporting categories for ‘borderline ?low grade’ and ‘borderline ?high grade’. Conclusions: There is diversity in the use of the category ‘borderline’ in the UK. The proposed revised BSCC terminology with separate categories for borderline ?low grade, borderline ?high grades and borderline ? glandular dyskaryosis reflects the opinion of the majority of respondents to the questionnaire.     

Atypical squamous cells and low‐grade squamous intraepithelial lesion in cervical cytology: cytohistological correlation and implication for management in a low‐resource setting

N. Gupta, R. Srinivasan, R. Nijhawan, A. Rajwanshi, P. Dey, V. Suri and L. Dhaliwal Atypical squamous cells and low‐grade squamous intraepithelial lesion in cervical cytology: cytohistological correlation and implication for management in a low‐resource setting Objectives: To perform an audit of all cervical smears reported as atypical squamous cells (ASC) and low‐grade squamous intraepithelial lesion (LSIL) as in the Bethesda system (TBS) 2001, and determine their histological follow‐up and outcome when available, in order to define the threshold for colposcopic referral. Material and methods: A total of 25 203 cervical smears were screened over a period of 3 years (January 2006 – December 2008) and all ASC and LSIL smears were reviewed with the corresponding histological follow‐up. All cervical intraepithelial neoplasia (CIN) grade 2 lesions and above (CIN2+) were considered as clinically significant lesions for analysis. Results: Out of 25 203 cervical smears, 424 (1.7%) were reported as ASC and 113 (0.4%) as LSIL. Additionally, three were reported as atypical cells, not otherwise specified. The ASC : SIL ratio was 2.18 : 1. Follow‐up histology was available in 153 (36.8%) of the ASC cases and revealed CIN2+ lesions in 22 (14.4%). Follow‐up histology was available in 50 (44.2%) of LSIL cases and revealed clinically significant abnormalities in five (10%), all of which were CIN2. CIN3 and invasive squamous carcinomas were seen in 5.9% and 1.4%, respectively, of cases of ASC, and not seen in LSIL. Reclassification of ASC smears into ASC‐US (ASC‐undetermined significance) and ASC‐H (ASC‐ high grade SIL not excluded) revealed ASC‐H in 2.6% of all ASC smears, with a clinically significant outcome in 45.4%. Conclusion: In a low‐resource setting where human papillomavirus testing is unaffordable, the threshold for colposcopic referral and follow‐up histology should be ASC rather than SIL.     

Plural light chains in a single plasma cell of a monoclonal gammopathy undetermined significance case: An ultrastructural study

A 44-year-old man was found to have M-proteins of IgG consisting of kappa- and lambda-chains in serum without lymphadenopathy or splenomegaly. The serum concentrations of IgG, IgA and IgM were within normal limits. Bone marrow examination showed normal cellular marrow containing 6.3% of plasma cells with no abnormal features. No chromosomal abnormality was observed at all. The patient was diagnosed as having monoclonal gammopathy of undetermined significance. The bone marrow plasma cells possessed free kappa- and lambda-chains in Golgi apparatus, rough endoplasmic reticula and cytoplasmic matrices. Plural light chains were simultaneously produced with the same heavy chain in a plasma cell by immunoelectron microscopy. This is the first report in the world of a monoclonal gammopathy of undetermined significance producing plural light chains with the same heavy chain.     

Atypical glandular cells: criteria to discriminate benign from neoplastic lesions and squamous from glandular neoplasia

OBJECTIVE: To evaluate the presence of some criteria in cervical smears with atypical glandular cells and their correlation with histological patterns to identify pre-neoplastic and neoplastic lesions. METHODS: Seventy-three women referred with an atypical glandular cell smear, who had undergone conization or hysterectomy, were included in this study. Referral Pap smears were reviewed using the set of 27 cyto-morphological criteria that was correlated with the histological diagnosis. RESULTS: Histological results showed intraepithelial or invasive neoplasia in 35 (48%) cases and benign lesions in 38 (52%) cases. After logistic regression and decision tree analysis an increased nuclear/cytoplasmic ratio and the presence of dyskeratotic cells were strongly associated with intraepithelial or invasive neoplasia and the differential cyto-morphological criteria for glandular lesions were decreased cytoplasm, irregular nuclear membranes and the presence of nucleoli. CONCLUSION: The analysis of individual cyto-morphological criteria can better predict intraepithelial or invasive neoplasia and differentiate glandular from squamous lesions.     

The ASCUS : SIL ratio and the reference laboratory pathologist

The atypical squamous cells of undetermined significance (ASCUS) : squamous intraepithelial lesion (SIL) ratio was proposed to monitor laboratory use of the ASCUS diagnosis. This study addresses problems associated with comparing pathologists by this means. An intuitive example showed the ASCUS : SIL ratio depends on the prevalence of smears from patients who actually have SIL. In this study of 2000 cervical smears, each of five pathologists made 400 diagnoses. Differences among proportions of SIL diagnoses were statistically significant; differences among proportions of ASCUS diagnoses were not. Had an ASCUS : SIL ratio upper limit of 3.0 been used, two pathologists would have been misidentified as having high ASCUS diagnosis rates. Unlike the situation for laboratories, potential variability in SIL prevalence requires caution in the use of this ratio in assessing pathologists. An alternative measure that is independent of prevalence, the ASCUS : SIL odds ratio, is posited.     

Atypical squamous cells of undetermined significance in women over 55. Comparison with the general population and implications for management.

OBJECTIVE: To determine the significance of atypical squamous cells of undetermined significance (ASCUS) in patients 55 years or older. STUDY DESIGN: From January 1994, to January 1997, 8,175 cervicovaginal smears were obtained from patients 55 years or older (mean age, 64.8; range, 56-84) at University Hospitals of Cleveland. Ninety-six of these patients were diagnosed with ASCUS only or ASCUS with a qualifying statement on the smear. Patient records, follow-up cervicovaginal smears and biopsies were reviewed for a period of one to four years following the diagnosis of ASCUS. RESULTS: The incidence of ASCUS only or ASCUS with a qualifying statement for patients 55 years or older was 1.8%. The ASCUS:SIL ratio was 2.6:1. An estrogen stimulation test was recommended in two cases. Women older than 55 with ASCUS were three times more likely to be receiving hormonal replacement therapy than similar-aged women with normal cervicovaginal smears. Follow-up cervicovaginal smears or biopsies were obtained on 93 (80 cervicovaginal smears, 13 biopsies). The results were the following: LSIL (13), squamous carcinoma in situ (1) and ASCUS (53); the remainder of the cases were normal. In the patients who received a second diagnosis of ASCUS, follow-up cervi covaginal smears or biopsies revealed low grade dysplasia in six. CONCLUSION: Although the incidence of ASCUS and the frequency of underlying dysplasia is lower in postmenopausal women than the general population, there is still a real risk that a postmenopausal woman with ASCUS has underlying intraepithelial neoplasia. Therefore, these patients should be managed as is the general population.     

Eliminating the diagnosis atypical squamous cells of undetermined significance: impact on the accuracy of the Papanicolaou test

OBJECTIVE: To assess eliminating the diagnosis "atypical squamous cells of undetermined significance" (ASCUS) from the Bethesda System for Reporting Cervical/Vaginal Cytological Diagnoses and analyze its impact on the sensitivity and positive predictive value of Pap smears. STUDY DESIGN: A total of 166 previously diagnosed ASCUS cases with follow-up biopsy results available were prospectively downgraded to within normal limits/benign cellular changes or upgraded to specific squamous intraepithelial lesions (SILs) or the malignant category. These review cytodiagnoses were compared with the histologic outcome. The impact on the sensitivity and positive predictive value of Pap smears was also assessed. RESULTS: Though there was a decrease in the sensitivity of the Pap smear from 100% to 76.3% for SIL overall and from 100% to 80% for high grade SIL (HSIL) alone, there was an improvement in the positive predictive value of diagnosing SIL from 46% to 85% and from 6% to 15% for HSIL alone. CONCLUSION: The ASCUS diagnosis can be minimized to a great extent, if not eliminated completely. The "ASCUS-favor reactive" group can be eliminated, while the diagnoses "ASCUS favor SIL" and "ASCUS-not otherwise specified" should be used sparingly.     

Morphologic, patient and interpreter profiles of high-risk human papillomavirus-positive vs.-negative cases of atypical squamous cells of undetermined significance

OBJECTIVE: To define the morphologic and patient profiles, if any, that distinguish high-risk human papillomavirus (HR-HPV)-positive atypical squamous cells of undetermined significance (ASCUS) from HR-HPV-negative ASCUS and to compare individual and laboratory reporting rates with the national averages. STUDY DESIGN: One hundred fifty liquid-based cervicovaginal preparations (ThinPrep, Cytyc Corporation, Boxborough, Massachusetts, U.S.A.) with a diagnosis of ASCUS and a reflex HR-HPV test were assessed for the following features: background patient information, cell morphology, cell patterns and interpreter profiles. Fisher's Exact test (2-tailed) was used to calculate the exact probability of obtaining results by chance. RESULTS: The median age of the HR-HPV-positive patients was approximately 11 years younger than the HPV-negative group, and pregnant patients were also more apt to be HPV positive. Atypical cells in greater numbers and in groups as opposed to single cells correlated more often with HR-HPV-positive individuals. Koilocytelike changes and parakeratosis were more frequently associated with HR-HPV, but the presence of Trichomonas was usually a negative predictor. CONCLUSION: In cases diagnosed as ASCUS, there are certain cytologic features and patient types that are more likely to be associated with HR-HPV positivity. This could be used in everyday practice to further fine tune the diagnosis of ASCUS. Monitoring individual and laboratory ASCUS rates with HR-HPV positivity can be an important quality improvement indicator.     

Diverse glandular pathologies coexist with high-grade squamous intraepithelial lesion in cyto-histological review of atypical glandular cells on ThinPrep specimens

Objective: To identify in cytology, high‐grade squamous intraepithelial lesions with endocervical glandular extension in cases previously diagnosed as atypical glandular cells (AGC), analyse possible reasons for the diagnostic pitfall and document the frequency of glandular pathology coexisting with high‐grade cervical intraepithelial lesion in histology. Methods: Thirty‐nine ThinPrep® cervical smear (Pap) tests reported as AGC of undetermined significance and showing high‐grade lesions on histology [cervical intraepithelial neoplasia (CIN) 2 or 3, endometrial or extrauterine adenocarcinoma] were reviewed retrospectively to identify the cases of high‐grade squamous intraepithelial lesion with endocervical glandular extension, using the Bethesda 2001 system. Cyto‐histological correlation was performed. Results: A high frequency of diverse glandular pathologies coexisted with high‐grade cervical intraepithelial lesions on histology. This included endocervical glandular extension in 63%, benign glandular pathology in 33% and pre‐neoplastic or malignant glandular pathology (endocervical glandular dysplasia, adenocarcinoma in situ and metastatic breast carcinoma) in 17% cases. On cytology, the sensitivity was 40%, specificity was 80% and positive predictive value was 86% for endocervical gland extension in high‐grade squamous intraepithelial lesions. Conclusions: Special efforts to recognize endocervical glandular extension in high‐grade squamous intraepithelial lesions and glandular neoplasia coexisting with squamous intraepithelial lesions from the heterogeneous category of AGC can contribute to increasing the diagnostic accuracy. The identification of endocervical glandular extension on cervical cytology would alert the gynaecologist to perform a thorough assessment of the endocervix during colposcopy. This could also help to decide on the need to perform deeper conization rather than loop electrosurgical excision procedure to ensure negative margins when colposcopic biopsy shows CIN 2 or 3.     

Atypical cells in the urinary sediment: a protocol for cytological analysis of the urinary sediment

Introduction:  The Department of Clinical Chemistry of the General Hospital of Móstoles (Madrid, Spain) has for many years diagnosed the presence of atypical cells in the urinary sediment (ACUS), but this finding only led to a comment in the final report of the urinalysis, informing the clinician of this fact in case he/she decided to perform further studies in these patients.
Methods:  Since 2004, the Clinical Chemistry Department has implemented a new protocol together with the Department of Surgical Pathology of the Hospital, according to which all the urinary sediment samples with ACUS are sent for cytological analysis. In this report, we comment on the results corresponding to 99 samples.
Results:  With this new strategy, we can directly diagnose if the ACUS correspond to a carcinoma or to another process, and this has allowed us to reduce time until diagnosis in our patients and also to avoid unnecessary studies in negative cases. We comment on our results with this new management strategy.     

Atypical glandular cells in cervical smears: histological correlation and a suggested plan of management based on age of the patient in a low-resource setting

Objectives:  To perform an audit of all smears reported as atypical glandular cells (AGC) using the Bethesda system (TBS) 2001.
Methods:  A total of 18 376 cervical smears were screened from January 2005 to June 2007, of which 65 cases were reported as AGC. Follow-up histology was available in 31 cases (47.7%), in whom a detailed cytological/histological correlation was carried out.
Results:  AGC constituted 0.35% of all Pap smears. Follow-up histology was normal or benign in 20 cases, whereas a squamous or glandular abnormality was seen in 11 cases. Squamous abnormalities included one case each of cervical intraepithelial neoplasia (CIN)1, CIN2 and CIN3 and five cases of squamous cell carcinoma. All glandular epithelial abnormalities were endometrial in origin and included two endometrial adenocarcinomas and one uterine serous carcinoma. Neither in situ nor invasive adenocarcinoma of the endocervix was observed. Review of smears and reclassification as AGC, not otherwise specified and favour neoplasia revealed a higher proportion of abnormality in the latter group, reaffirming the utility of subtyping. The median age of women with AGC was 41 years. The outcome was analysed with respect to the median age. In women aged equal or more than 40 years, AGC reflected a high-grade squamous or glandular epithelial abnormality in 50% of cases compared with none in those less than 40 years old ( P  = 0.010).
Conclusion:  The age of the woman as well as the subtype of atypical glandular cells influences outcome and hence must be taken into consideration while formulating an acceptable management strategy in these women in a low-resource setting.     

Interobserver concordance in the assessment of features used for the diagnosis of cervical atypical squamous cells and squamous intraepithelial lesions (ASC‐US,ASC‐H,LSIL and HSIL)

G. Bigras, J. Wilson, L. Russell, G. Johnson, D. Morel and M. Saddik
Interobserver concordance in the assessment of features used for the diagnosis of cervical atypical squamous cells and squamous intraepithelial lesions (ASC‐US, ASC‐H, LSIL and HSIL) Objectives: Given the well‐known poor reproducibility of cervical cytology diagnosis, especially for atypical squamous cells of undetermined significance (ASC‐US) and low‐grade squamous intraepithelial lesion (LSIL), this study surveyed reproducibility in the assessment of individual cytomorphological features. Methods: One hundred and fifty cells or groups of cells, with a variety of morphological appearances, including normal cells, high‐grade squamous intraepithelial lesion (HSIL), LSIL, ASC‐US and ASC cannot exclude HSIL (ASC‐H), were precisely marked on 150 different liquid‐based cytological preparations. They were analysed by 17 observers who assessed 17 cytological features including nuclear features (chromatin texture, nuclear outline, nuclear shape, etc.), cytoplasmic features (cell shape, cytoplasmic staining, cytoplasmic clearing, etc.) and group characteristics (nuclear polarity, cellular density, etc.). A total of 43 350 data scores were collected in a database using a web‐based survey. Kendall’s W and relative entropy indexes were utilized to compute concordance indexes of respectively ordinal and nominal variables. Results: Nuclear features have significantly lower reproducibility (0.46) compared with other cytological features (0.59). The feature with least agreement is assessment of chromatin texture. A small but significant difference in concordance was found between two subsets of observers with different levels of experience. Conclusion: Most previous studies assessing reproducibility of cytological diagnoses show, at best, moderate reproducibility among observers. This study focused on agreement regarding the presence of constituent morphological features used to recognize dyskaryosis and various grades of squamous intraepithelial lesions. A map of reproducibility indexes is presented that highlights, for daily practice or teaching, the robustness of features used for cytological assessment, recognizing that diagnosis is always based on a combination of features.     

Resting potential of the mouse neuroblastoma cells: II. Significant contribution of the surface potential to the resting potential of the cells under physiological conditions

In the previous paper, we showed that the K⁺ channels of the mouse neuroblastoma cell (clone N-18) are closed at low concentration of external K⁺ ([K⁺]₀) including the physiological concentration for the cells. In the present study, the origin of the resting membrane potential of N-18 cells has been examined. (1) The resting membrane potential of N-18 cells was depolarized by increasing concentration of the polyvalent cations (La³⁺, Fe³⁺, Co²⁺, Ca²⁺, Sr²⁺, Mg²⁺) and by decreasing the pH of the medium. The input membrane resistance was slightly increased during the depolarization. The depolarization was not explained in terms of the diffusion of the cations across the membrane, since the trivalent cations of greater ionic size were effective at much lower concentrations than the divalent cations. The results obtained from the measurements of ⁸⁶Rb efflux suggested that the depolarization cannot be explained in terms of blocking of the K⁺ channels by the cations. (2) An increase in Ca²⁺ concentration from 0.3 to 1.8 mM induced depolarization of about 10 mV at low [K⁺]₀ where the K⁺ channels are closed, but did not induce any depolarization at high [K⁺]₀ where the channels are open. (3) In order to estimate the changes in the zeta-potential, the electrophoretic mobility of N-18 cells was measured under various conditions. There was a close correlation between the changes in the zeta-potential and those in the membrane potential in response to the polyvalent cations and proton. On the other hand, an increase in K⁺-concentration in the medium, which induced a large depolarization in the cells, did not affect the zeta-potential. (4) The results obtained were explained by an electrical circuit model for the membranes of N-18 cells. In this model, an electrical circuit for the membrane part carrying no selective ionic channels, in which changes in the surface potential directly affect the transmembrane potential, is connected in parallel to the usual circuit model representing selective ionic channel systems. It was concluded that the surface potential contributes significantly to the resting membrane potential of N-18 cells at low [K⁺]₀ where the K⁺ channels are closed.     

芳姜黄酮对人皮肤鳞状细胞癌A431细胞迁移、侵袭及凋亡的影响和机制研究

为研究芳姜黄酮(Ar-Turmerone)对人鳞状细胞癌A431细胞增殖、迁移、侵袭和凋亡的影响及机制。实验采用CCK-8法检测抑制率,吉姆萨染色观察细胞形态,划痕实验和Transwell小室实验研究细胞迁移和侵袭能力的变化,流式细胞仪检测细胞凋亡率。此外,通过实时荧光定量聚合酶链反应(Real-time PCR)与蛋白质印迹法(western blot)法检测mRNA和蛋白表达。siRNA阻断Notch1,Hes1和PTEN,检测相应的下游mRNA和蛋白的表达变化,流式细胞仪检测细胞凋亡率。结果发现,芳姜黄酮可以抑制A431细胞增殖,使细胞形态发生改变,抑制细胞体外迁移和侵袭能力,促进细胞凋亡。经过芳姜黄酮处理后,Notch1,Hes1,PTEN的mRNA和蛋白表达升高。沉默Notch1,Hes1 mRNA和蛋白表达低于单纯给药组,而沉默Hes1,PTEN mRNA和蛋白表达也低于单纯给药组;沉默PTEN后,与单纯给药组相比,细胞死亡率降低。总之,芳姜黄酮可以抑制人鳞状细胞癌A431细胞的增殖并促进其凋亡,且具有抑制体外迁移和侵袭的作用,其促进细胞凋亡的机制是通过Notch1/Hes1/PTEN途径实现的。     

Relationship between the shape and the membrane potential of human red blood cells

Summary Microscopic observations of isotonic suspensions of human red blood cells demonstrate that cell shape is unaltered when the transmembrane electrical potential, orE _m , is set in the range –85 to +10 mV with valinomycin at varied external K⁺, or K _o .E _m was measured with the fluorescent potentiometric indicator, diS-C₃(5), as calibrated by a pH method. Repeating Glaser's experiments in which echinocytosis was attributed to hyperpolarization, we found that at low ionic strength the pH-dependent effects of amphotericin B appear to be unrelated toE _m . The effects of increased intracellular Ca²⁺, or Ca _o , on echinocytosis and onE _m are separable. With Ca ionophore A23187 half-maximal echinocytosis occurs at greater Ca _o than that which induces the half-maximal hyperpolarization associated with Ca-induced K⁺ conductance (Gardos effect). Thus, cells hyperpolarized by increased Ca _o remain discoidal when Ca is below the threshold for echinocytosis. With A23187 and higher Ca _o , extensive echinocytosis occurs in cells which are either hyperpolarized or at their resting potential. The Ca-activation curve for echinocytosis is left-shifted by low K _o , a new observation consistent with increased DIDS-sensitive uptake of⁴⁵Ca by hyperpolarized cells. These results support the following conclusions: (1) the shape and membrane potential of human red blood cells are independent under the conditions studied; (2) in cells treated with A23187, the Gardos effect facilitates echinocytosis by increasing Ca.     

Effects of inhibitors of ion-motive ATPases on the plasma membrane potential of murine erythroleukemia cells

The membrane electric effects of N,N'-dicyclohexyl-carbodiimide (DCCD) and vanadate were studied in murine erythroleukemia cells (MELC), comparing the patch-clamp technique and the accumulation ratio (ARexp) of [3H]-tetraphenylphosphonium (TPP+). Electrophysiological measurements showed that both these inhibitors produce, at micromolar concentrations, a 20-30 mV hyperpolarization of resting potential (delta psi p) of MELC, which is abolished when the electrochemical equilibrium potential of K+ (EK) is brought close to zero. DCCD and vanadate turned out to have distinct targets on the plasma membrane of MELC (an H+ pump and the Na+,K(+)-ATPase, respectively). Measurements of ARexp showed that: (i) patch-clamp measurements of delta psi p were equivalent to those based on ARexp of antimycin-pretreated cells (ARANT); (ii) DCCD produced a strong increase in ARANT, that was antagonized by carbonyl cyanide p-trifluoromethoxyphenyl-hydrazone (FCCP) and diethylstilbestrol (DES); (iii) vanadate determined a marked increase in ARANT that was insensitive to FCCP, but antagonized by ouabain; (iv) incubation in high K+ medium (HK) brought ARANT to 1.0 in the controls, but did not lower this ratio below 3.0 in the presence of DCCD or vanadate; (v) the total amount of TPP+ taken up by the cells was in any case water extractable by a freezing and thawing procedure. On the whole, our data indicate that DCCD and vanadate hyperpolarize the MELC by increasing the K+ conductance and, at the same time, enhance the TPP+ binding, probably by changing the electrostatic potential profile of the plasma membrane. These effects seem to involve functional modifications of the target pumps, apparently related to the ion-occluding state of these enzymes.     

An assessment of the potential impact of dredging activity on the Tamar Estuary over the last century: Bathymetric and hydrodynamic changes

The Tamar Estuary, S.W. England, is a commercial and military port and the site of a major naval dockyard. Parts of the estuary require regular maintenance dredging and some capital dredging has been undertaken. The estuary is also assigned Special Area of Conservation (SAC) status under the European Habitats Directive and is an important site for migrating wildfowl and wading birds. As part of an assessment undertaken for a consortium of the port operators and regulatory authorities, we have analysed the ecological, physical, chemical and socio-economic impacts of dredging on the Tamar Estuary ecosystem. This paper focuses on the physical changes through the analysis of historical survey data and the use of hydrodynamic modelling. The objective was to evaluate whether dredging has influenced the estuary morphology or hydrodynamic regime and thus impacted on the ecological habitat. Bathymetric survey data collected between 1895 and 1968 were compared with multi-beam echo sounder data obtained in 2001. The paper survey records were digitised, geo-referenced and adjusted to the modern datum and units. The accuracy and limitations of this approach are discussed. Both sets of data were contoured and analysed using a GIS package. Comparisons between 1895 and 2001 hydraulics were made using a 1-D hydrodynamic and sediment transport model set up for the bathymetry at those times but ‘driven’ using a single, common, year-long data set for tides and river flows. The results suggest that although the deep channel in the region that is mainly south of the Tamar road bridge, is on average 0.5 m deeper in 2001 than it was in 1895, this has had a negligible effect on the area of intertidal mud and, thus, on habitat available for wading birds, and minimal impact on the large-scale hydrodynamics of the estuary.