Table 1.

Demographic and preoperative characteristics

	Pregnant n = 99	Non pregnant n = 1796	p
Age	30.1 ± 5.8	28.0 ± 9.0	< 0.001
BMI*	27.5 ± 5.7	24.0 ± 5.2	< 0.001
RLQ Tenderness			0.002
- Yes	83 (83.8)	1659 (92.4)
- No	16 (16.2)	137 (7.6)
Pain migration			0.27
- Yes	17 (17.2)	392 (21.8)
- No	82 (82.8)	1404 (78.2)
Guarding			0.011
- Yes	23 (23.2)	642 (35.7)
- No	76 (76.8)	1154 (64.3)
Rebound Tenderness			0.097
- Yes	20 (20.2)	500 (27.8)
- No	79 (79.8)	1296 (72.2)
Nausea and / or vomiting	25 (25.3)	498 (27.7)	0.59
- Yes
- No	74 (74.7)	1298 (72.3)
Duration of symptoms prior to presentation at ED			0.003‡
- < 24h	60 (68.2)	893 (51.9) ‡
- ≥ 24h	28 (31.8)	828 (48.1) ‡
- unknown	11	75
WBC (per nl)	13.6 ± 4.5	12.5 ± 4.5	0.014
CRP (mg/l)	40.2 ± 46.9	37.1 ± 55.6	0.30
Bilirubin (mg/dl)	0.48 ± 0.35	0.60 ± 0.43	0.009
Ultrasound (direct or indirect signs)			< 0.001
- Positive	41 (42.3)	1052 (60.1)
- Negative	56 (57.7)	698 (39.9)
No ultrasound available	2	46
Ultrasound (direct signs)			0.003
- Positive	33 (34.0)	865 (49.4)
- Negative	64 (66.0)	885 (50.6)
No ultrasound available	2	46
Perforation on Ultrasound			0.18
- Yes	1 (1.0)	69 (4.0)
- No	96 (99)	1681 (96.0)
No ultrasound available	2	46
Ultrasound: sensitivity	47.5%	63.5%	0.004
Ultrasound: specifity	82.4%	55.8%	0.032
Admission to surgery			0.90
≤ 12 hours	71 (71.7)	1299 (72.3)
> 12 hours	28 (28.3)	497 (27.7)

Data are mean ± SD or n (%) or median (IQR)

IQR interquartile range, SD standard deviation, BMI body mass index, CRP C-reactive protein, WBC white blood cell

^‡ Percentages and p-value refer to subgroup of patients with known duration of symptoms

* BMI was recorded at the time of hospital admission