Preoperative Misoprostol in Reducing Blood Loss in Total Abdominal Hysterectomy (TAH)

• operative blood loss [ Time Frame: duration of operation, up to 3 hours ] [ Designated as safety issue: No ]
  The total volume of blood loss was estimated by measuring the amount of blood accumulated in the aspiration equipment and the amount of blood on the surgical gauze using a alkaline haematin method.
  
  

• the requirement of blood transfusion [ Time Frame: from intra-operation to hospital discharge, up to 7 days ] [ Designated as safety issue: No ]
  
• the change in haemoglobin level after operation [ Time Frame: preoperative to 30 hours postoperative ] [ Designated as safety issue: No ]
  
• the incidence of side effects [ Time Frame: 30 minutes after misoprostol/placebo was given ] [ Designated as safety issue: Yes ]
  

Uterine leiomyoma is the commonest benign tumour affecting women in their reproductive age. Around 20-50% can cause symptoms that warrant treatment. Different medical therapies, including gonadotrophin releasing hormone analogues, mifepristone, progestins and androgens have been tried. However, most of the medical therapy have significant side-effects that would only allow a short-term treatment. Total abdominal hysterectomy is the definitive treatment for large, symptomatic fibroids. Operative mortality of total abdominal hysterectomy is rare. However, the operation may be associated with significant morbidities. Significant operative blood loss that required blood transfusion and oral iron supplement is not uncommonly encountered after total abdominal hysterectomy.

Various methods have been tried to reduce the operative blood loss during total abdominal hysterectomy. A course of hormonal therapy for a few months before operation aiming to shrink the size of fibroid(s) and reduce the vascularity is the commonest approach. Although it is effective, there are significant side effects and the cost of gonadotrophin releasing hormone analogues is high. Intramyometrial vasopressin injection has been reported, but serious complications have been reported.

Misoprostol, a prostaglandin E1 analogue, has been widely used in clinical practice in obstetrics and gynaecology. It stimulates uterine contractions and this increase in myometrial contraction will lead to contraction of the vessels supplying blood to the leiomyomas. Misoprostol has also been shown to increase the uterine artery resistance and reduce the blood flow to the leiomyomas. Study by Celik et al has shown that pre-operative misoprostol can reduce intra-operative blood loss and need for post-operative blood transfusion after abdominal myomectomy. Chang et al investigated the use of misoprostol and oxytocin in laparoscopy-assisted vaginal hysterectomy and found that the combination of pre-operative misoprostol and intra-operative oxytocin can reduce blood loss by 200 ml. As misoprostol can stimulate uterine contraction and reduce uterine blood flow, based on the hypothesis that pre-operative misoprostol may redistribute the blood from the diseased uterus back to the circulation hence reducing operative blood loss during total abdominal hysterectomy, we use a double-blind randomized controlled trial to investigate whether a single dose of sublingual misoprostol before total abdominal hysterectomy +/- salpingo-oophorectomy for symptomatic uterine leiomyomas can reduce operative blood loss and need for post-operative blood transfusion.