The HYsteroscopic Miscarriage MaNagement (HYMMN) pilot randomized-controlled trial

To evaluate the feasibility of performing a full-scale, adequately powered, multi-center randomized controlled trial (RCT) assessing the effectiveness of office hysteroscopy (OH) for the treatment of retained pregnancy tissue (RPT) after miscarriage, compared with standard treatment (ST) (expectant/medical/surgical), on future pregnancy outcome.

Single-center pilot RCT performed at Birmingham Women's Hospital, UK. Patients opting for non-surgical miscarriage management at ≤14 weeks gestation who wanted to conceive as soon as possible were recruited and offered a transvaginal ultrasound scan (TVUS) eight weeks later to check for the presence of RPT. Patients with RPT were randomized in a 1:1 ratio using a computer-generated online random allocation sequence to either OH (performed using the TruClear 5.0 hysteroscopic tissue retrieval system) or ST (the type of which was recommended based on symptoms, urinary pregnancy test and scan findings).

158 participants were approached for inclusion into the trial, of which 149 (94.3%) agreed. Of the 126 that underwent TVUS, RPT were diagnosed in 42 patients (33.3%). 21 patients were randomized to OH, of whom 18 underwent the procedure because three fell pregnant after their TVUS. OH was deemed acceptable to all patients without any serious complications. 21 patients were randomized to ST where 16 patients (76%) were recommended expectant management and five (24%) were recommended surgical management. 115 patients (91%) were able to provide pregnancy data, however, the study was not powered to show a clinically significant difference.

A full-scale, adequately powered, randomized clinical trial investigating OH against ST for the treatment of RPT following miscarriage is clinically relevant and feasible owing to high rates of participation, acceptability and satisfaction and low rates of attrition associated with the proposed interventions.