Morbidity of surgical abortion depends on gestational age, the method of termination, age and parity. The complications of surgical abortion are infection, cervical laceration, incomplete evacuation, uterine perforation, hemorrhage and anesthetic complications [1, 2].
Surgical methods used for abortion are dilatation and curettage, dilatation and evacuation, hysterotomy and hysterectomy. Suction evacuation of the uterus remains one of the most popular options for termination of first trimester pregnancies. Cervical ripening before first-trimester surgical termination of pregnancy facilitates the procedure and reduces the operative morbidity [3, 4]. Various cervical priming ...view middle of the document...
The studies have shown that nitric oxide donors can effectively be used for cervical ripening in term [12, 13, 14]. Although it is less effective than prostaglandin analogues but it has less side effects.
The current study was undertaken to investigate the efficacy of isosorbide mononirate (IMN) for cervical priming prior to first trimester evacuation of the uterus. The primary objective was to assess the efficacy of isosorbide mononitrate in dilatation of cervix. Duration of operation, blood loss during the operation and incidence of side effects were recorded as secondary objectives.
Materials and Methods
This study was conducted at Ramathibodi Hospital, Mahidol University, Thailand, from October 2008 to June 2009. The protocol was approved by the Ethics Committee of the Faculty of Medicine, Ramathibodi hospital. Written informed consent was obtained from all women. Inclusion criteria were pregnant women with gestational age less than 12 weeks, undergoing suction evacuation under general anesthesia, no history of hypotension and ultrasonography confirmed non-viable pregnancy. Women who had previous cervical surgery, inevitable abortion, incomplete abortion, underlying medical diseases, allergy to isosorbide mononitrate and unwilling to participate in the trial were excluded.
Sample size was calculated to have a power of 90% at the 5% significance level to detect a standardized difference of 1.2 mm of cervical dilatation . Twenty-four women were needed in each group.
The study was conducted in a double-blind manner. After informed consents were obtained, the patients were allocated into two groups using computer-generated randomization, sequentially number sealed opaque envelop, to receive either a tablet of 20 mg of isosorbide mononitrate or a tablet of identical appearing placebo (lactose filler). The author performed pelvic examination to rule out inevitable abortion (preexisting cervical dilation detectable by pelvic exam but the conceptus has yet to be expelled). The drug was placed in the posterior vaginal fornix 4 hours before suction evacuation by one of the authors. Blood pressure and pulse rate were recorded before drug administration and hourly until the procedure commenced. Women were asked to report to the nurses when they had abnormal symptoms such as palpitation, dizziness, fainting, nausea and vomiting. Cervical dilatation was measured before suction evacuation under general anesthesia by the obstetric residents. All the obstetric residents were trained to measure the cervical dilatation to reduce inter-observer variation. Cervical dilatation was assessed before suction evacuation using Hegar’s dilators starting from no. 10, followed by subsequent smaller size until it passed freely through the internal os. The largest size of the dilator that passed through the internal os without forcing was recorded. If the cervical dilatation was less than 6 mm, then the cervix would be dilated to Hegar no. 6, at which the...