3 | Results
During the study period 50 pregnant women were appendectomized and 38 155 who gave birth without appendectomy. During the same period 793 non-pregnant fertile women underwent appendectomy for suspected acute appendicitis (control group). Of the pregnant women, 39 (78%) were operated during the first half and 11 (22%) during the second half of pregnancy (54% were in the first trimester, 36% in the second, and 10% in the third trimester). The pregnant women were 32 +5-years-of-age, and the non-pregnant control group 31 + 8 years.
Details of pregnancy, outcome, and complications among women with and without appendectomy are presented in Table 1. There was one case of legal abortion after appendectomy, one extrauterine pregnancy, one spontaneous miscarriage (4th gestational week), and two cases with abortus imminens (foetal death before surgery). One woman was a tourist in Sweden and was delivered in her home country. There were no differences in birth or pregnancy complications between the two groups.
Table 2 shows grade of appendicitis, type of surgery, complications, and prophylactic treatment among pregnant and non-pregnant women with appendectomy. LapApp was used in 39 of 50 (78%) pregnant women and in 770 of 793 (97%) non-pregnant women (p < 0.001). OpenApp was used in 11 pregnant women (8 of these > 20 weeks of gestation), and in 7 non-pregnant women. Twelve per cent (n = 6) of pregnant women operated had an innocent appendix, 4 (36%) > 20 weeks gestation and 2 (4%) < 20 weeks). The corresponding figure in the non-pregnant control group was 2.1% (p = 0.03).
In pregnant women, the rate of perforated appendicitis was 12% (6/50), where no perforation was seen in the second half of pregnancy. In the non-pregnant control group, the rate was 19% (p = 0.03). Three pregnancy complications were noted: one case of early foetal loss (4th week), one case of contractions, and one newborn with flaccid moderate hypoxic ischaemic encephalopathy (HIE = 2). Early neonatal lumbal puncture showed signs of meningitis, but cultures were negative. There was no sign of acute asphyxia. However, the patient had been admitted to another hospital for suspected appendicitis 3 months earlier. Ultrasound indicated appendicitis, but the decision was taken to refrain from surgery.
In the pregnant appendectomy group, there were 3 (6%) surgical complications and in the non-pregnant control group 31 (3.9%) (p= 0.001). Intra-abdominal abscess and paralytic ileus were the dominant surgical complications (Table 2). No reoperation occurred within 30 days in the pregnant women group, but in 2 of the non-pregnant group. Two pregnant women (4%) were readmitted within 30 days, one for contractions that needed cerclage and one with a postoperative abscess. In the non-pregnant group, 14 (1.6 %) were readmitted within 30 days (p = 0.4). No death occurred within 30 days.
Histopathology examination of the appendix was performed in 88 % of pregnant cases (n = 44) and in 84.9 % (n = 673) in the non-pregnant control group. Of these 2.1 % had an innocent appendix, 0.6 % a tumour (n = 5), and “other diagnosis” in 0.6 %.
Seventy-four per cent (37/50) of appendectomy cases during pregnancy were treated with low molecular weight heparin after surgery, in most cases for 7 days. No case of postoperative venous thromboembolic event (VTE) was registered.
Diagnostic laboratory test results are presented in Table 3. All 6 pregnant women with perforated appendicitis had a low S-Na (< 136 mmol/L). White blood cell count was> 16 x 109/L in 36% (18/50) of appendectomy cases. CRP was > 20 mg/L in 60% (30/50) of cases and < 10 mg/L in 15% (6/50). Ultrasound diagnosis of appendicitis showed 100% specificity and 66% sensitivity (33/50) giving a high positive predictive value (PPV = 100%), while the negative predictive value was lower.
Times associated with appendectomy are presented in Table 4. There was a highly significant longer time-to-surgery in the non-pregnant control group compared to both early- and late pregnancy groups (p = 0.001 and p = <0.001, respectively). There were no significant differences in operation times or total time-in-surgery between the groups. Total in-hospital stay was significantly longer in the late pregnancy group compared to the non-pregnant control group (p = 0.02).
The mean annual incidence rate (IR) of appendectomy in Stockholm County for females ages 20 to 44 years was 132/100,000 women/year (95% CI 123‒141), decreasing from IR = 137 (95% CI 115‒164) for women aged 20 to 24 to IR = 89 (95% CI 73‒107) for those aged 40 to 44. The rate of appendectomy among delivering women was 115/100 000 (1/870) and the rate of appendicitis 99.6/100 000 (1/1004). Of these 33/44 (75%) occurred in early pregnancy (< 20 weeks) and 11/44 (25%) after 20 weeks of gestation. Thus, the odds of late pregnancy appendectomy were 3 times less in late pregnancy. Since, 7/11 late appendectomies had appendicitis, the true odds of appendicitis were even lower in late pregnancy.