Objective: To study the association between patient-related risk factors and severe maternal morbidity in women with tubal ectopic pregnancy (EP). Furthermore, to identify substandard care factors in clinical care management of EP. Design: Case-control study. Setting: Not applicable. Patient(s): Case subjects were from the LEMMoN study, a prospective nationwide cohort study. Control subjects were from the ESEP study, an international multicenter randomized controlled trial. Intervention(s): Case subjects were women with tubal EP complicated by severe intra-abdominal hemorrhage necessitating blood transfusion of ≥4 units of packed red blood cells peri- or postoperatively. Control subjects were women with tubal EP who were hemodynamically stable and surgically treated. Main Outcome Measure(s): Patient-related risk factors as: maternal age, gestational age, previous EP, Chlamydia infection, pelvic inflammatory disease, assisted reproductive techniques, and serum hCG level. Substandard care categories classified as unawareness of the clinician, misdiagnosis, and nonadherence to the guideline on EP. Result(s): Twenty-nine case subjects and 99 control subjects were included. The mean serum hCG level was significantly higher in case subjects compared with control subjects, but we found no reliable cutoff level of serum hCG to rule out maternal morbidity. Other risk factors did not differ significantly. Substandard care was scored more often in case subjects (43%) than in control subjects (14%), mainly concerning misdiagnosis. Conclusion(s): No patient-related risk factors for severe intra-abdominal hemorrhage in women with tubal EP were identified. Our findings underpin the importance of awareness of EP among young fertile women and care providers and clinical care management according to the guidelines to prevent severe maternal morbidity. © 2012 American Society for Reproductive Medicine, Published by Elsevier Inc.