Devising New Management Protocol Based on Sonographic Sensitivity for the Detection of Retained Products of Conception

Abstract

Objective:  To assess the accuracy of ultrasonography for the detection of retained products of conception in post partum and post abortal patients with Trans abdominal sonography using conventional medium frequency probes.

Material and methods:  Out of 289 patients referred by the Gynaecology Department with strong clinical suspicion of RPOC on clinical examination, 179 patients had D&C after sonographic evidence favouring RPOC. Sonographic criteria used for RPOC were echogenic, echopenic or mixed echogenecity uterine cavity mass with anteroposterior dimension equal to or exceeding 10 mm. We did not take into account the D&C carried out on clinical suspicion as this study was not designed for that and we wanted to know the sensitivity of Ultrasonography alone for detection of RPOC. For statistical analysis patients were divided into three groups depending on the antero posterior measurement of endometrial mass. Group I, endometrial mass thickness 10-12 mm, Group II, endometrial mass measurement 13-15 mm, Group III, anteroposterior endometrial mass thickness of 16-20 mm and Group IV with endometrial mass thickness of 21 mm onwards. Extracted material was sent for histopathology. Record of sonographic findings was matched with retrieved histopathology reports and sensitivity of sonography for the detection of RPOC was calculated.

Results:  134 patients were found to have RPOC. This constituted 75% overall accuracy. Remaining 45 patients, wrongly labeled as having RPOC on sonographic evaluation, were mostly within first week of delivery or induced abortion. Blood clots and necrotic material closely mimicked RPOC in these patients but could not be differentiated from residual trophobla-stic tissue, chorionic villi or fetal parts even by experienced radiologist. Sensitivity of sonography was noted to be alarmingly low in Group I and II patients (31% aggregate) whereas in Group III and IV it approached 81% and 95% respectively.

Conclusion:  75% sensitivity for detection of RPOC led to 25% patients undergoing unnecessary D&C. Considering the possibility of complications, both minor as well as major, following this interventional procedure, it is recommended that clinical impression as well as sonographic findings should be combined before proceeding on to uterine evacuation and if findings are equivocal on any of these, a waiting period of 24 to 48 hours may be observed and patient reviewed before operative procedure. This protocol should be given very serious consideration in patient with endometrial mass thickness of 15 mm or less.