Background: Hereditary haemorrhagic telangiectasia (HHT) is a dominantly inherited genetic vascular disorder that has prevalence of 1:5000 to 1:8000, and which is characterised by recurrent epistaxis, cutaneous telangiectasia, and arteriovenous malformations (AVMs) that affect many organs including the lungs, gastrointestinal tract, liver, and central nervous system. The aim here was to carry out a review of the literature on HHT complications during pregnancy in order to guide management decisions. Main body: A literature review was carried out to analyse all publications on complications that occurred during pregnancy in women with HHT. The PubMed/Medline and Scopus databases were searched. The complications observed in HHT women during pregnancy were then described. The authors identified 5 case series and 31 case reports that describe the evolution of 1577 pregnancies in 630 women with HHT. The overall maternal death rate described in the case series was estimated at 1.0% of pregnancies in the case series and 2 maternal deaths occurred in 31 pregnancy case reports. Severe maternal complications occurred in 2.7 to 6.8% of pregnancies in the case series. Severe complications occurred mostly in the second and third trimester in non-diagnosed and non-screened HHT patients. Severe complications were related to visceral involvement. The most frequent complications were related to pulmonary arteriovenous malformations (PAVMs) (haemothorax (n = 10), haemoptysis (n = 4), and severe hypoxaemia (n = 3)). Neurological complications were related to PAVMs in one case (right to left shunt) and to cerebral arteriovenous malformations (CAVM) and intracranial haemorrhage in 2 cases. Complications were related to hepatic arteriovenous malformations (HAVMs) in 8 cases (acutely decompensated heart failure due to hepatic involvement (n = 1), dyspnoea related to heart failure (n = 5), and hepatobiliary necrosis (n = 2)). Conclusion: Based on the literature review, most pregnancies in HHT women occur normally. However, these pregnancies should be considered high-risk, given the potential life-threatening events related to AVM rupture. Furthermore, there is currently no international consensus regarding the medical follow-up of pregnancy in women with HHT and the aim here was to carry out a review of the literature in order to guide screening and management decisions for this rare disease.

Objective To retrospectively describe a large series of pregnancies in women with hereditary haemorrhagic telangiectasia followed in our reference centre, plus neonatal outcomes, to better understand the risks of complications and to improve their prevention. Design A retrospective descriptive study conducted through a phone questionnaire. Setting Reference centre for hereditary haemorrhagic telangiectasia in Lyon, France. Population Women meeting the following criteria: (1) alive and aged ≥18 years; (2) with a definite clinical and/or genetic diagnosis of hereditary haemorrhagic telangiectasia; and (3) with at least one full‐term pregnancy. Main outcome measures Maternal and perinatal outcomes of pregnancies in women with hereditary haemorrhagic telangiectasia. Results Five hundred and sixty‐two pregnancies were reported in 207 women with hereditary haemorrhagic telangiectasia. A total of 271 complications (48.2%) were registered. Of these, 149 (55%) non‐specific complications, 110 (40.6%) non‐severe specific complications and 12 (4.4%) severe specific complications were registered. There were four cases of haemoptysis and two cases of transient ischaemic attack related to pulmonary arteriovenous malformations. Four patients had severe decompensated dyspnoea, related to pulmonary arteriovenous malformations in three cases and to pulmonary arteriovenous malformations associated with severe hepatic arteriovenous malformations in one case. Hepatobiliary necrosis occurred in one case. Epidural or spinal anaesthesia was performed in 139 of 452 deliveries (31%), without complications. There were 12 reports of congenital anomalies in 461 live births (3%). Conclusions Most pregnancies in hereditary haemorrhagic telangiectasia women are uneventful; complications are rare but can be severe. Women thus need to be educated about screening and possible pregnancy‐related risks before becoming pregnant.

Objectives: To evaluate short- and long-term safety and efficacy of embolization with Onyx® for recurrent pulmonary arteriovenous malformations (PAVMs) in hereditary hemorrhagic telangiectasia (HHT). Methods: In total, 45 consecutive patients (51% women, mean (SD) age 53 (18) years) with HHT referred to a reference center for treatment of recurrent PAVM were retrospectively included from April 2014 to July 2021. Inclusion criteria included evidence of PAVM recurrence on CT or angiography, embolization using Onyx® and a minimal 1-year-follow-up CT or angiography. Success was defined based on the standard of reference criteria on unenhanced CT or pulmonary angiography if a recurrence was suspected. PAVMs were analyzed in consensus by two radiologists. The absence of safety distance, as defined by a too-short distance for coil/plug deployment, i.e., between 0.5 and 1 cm, between the proximal extremity of the primary embolic material used and a healthy upstream artery branch, was reported. Results: In total, 70 PAVM were analyzed. Mean (SD) follow-up was 3 (1.3) years. Safety distance criteria were missing in 33 (47%) PAVMs. All procedures were technically successful, with a short-term occlusion rate of 100% using a mean (SD) of 0.6 (0.5) mL of Onyx®. The long-term occlusion rate was 60%. No immediate complication directly related to embolization was reported, nor was any severe long-term complication such as strokes or cerebral abscesses. Conclusions: In HHT, treatment of recurrent PAVM with Onyx® showed satisfactory safety and efficacy, with an immediate occlusion rate of 100% and a long-term rate of 60%.