Thrombophilia can lead to thrombosis at the maternal or the fetal interface
Thrombosis on the maternal side may lead to severe preeclampsia, intrauterine growth restriction, abruptio placenta, or fetal loss. Thrombosis on the fetal side can be a source of emboli that bypass hepatic and pulmonary circulation and travel to the fetal brain and cause a catastrophic event, such as perinatal arterial stroke via arterial thrombosis, cerebral sinus venous thrombosis, or renal vein thrombosis.
Perinatal and neonatal stroke
Perinatal stroke is defined as a cerebrovascular event that occurs between 28 weeks of gestation and 28 days of postnatal age.30 Incidence is approximately 17 to 93 cases for every 100,000 live births.9
Neonatal stroke occurs in approximately 1 of every 4,000 live births.30 In addition, 1 in every 2,300 to 4,000 newborns is given a diagnosis of ischemic stroke in the nursery.9
Stroke and cerebral palsy
Arterial ischemic stroke in the newborn accounts for 50% to 70% of cases of congenital hemiplegic cerebral palsy.11 Factor V Leiden mutation, prothrombin gene mutation, and a deficiency of protein C, protein S, and antithrombin III have, taken together in two studies, been identified in more than 50% of cerebral ischemic strokes.31,32 In addition to these thrombophilias, important risk factors for perinatal and neonatal stroke include:
- thrombosis in placental villi or vessels
- infection
- use of an intravascular catheter.33
The mechanism that underlies perinatal stroke is a thromboembolic event that originates from either an intracranial or extracranial vessel, the heart, or the placenta.10 A recent meta-analysis by Haywood and colleagues found a statistically significant correlation between protein C deficiency, MTHFR C677T (methyltetrahydrofolate reductase), and the first occurrence of arterial ischemic stroke in a pediatric population.34 Associations between specific thrombophilias and perinatal stroke, as well as pediatric stroke, have been demonstrated (TABLE 4), but we want to emphasize that the absolute risks in these populations are very small.34,35 In addition, the infrequency of these thrombophilias in the general population (TABLE 3) means that their positive predictive value is extremely low.
TABLE 4
Fetal thrombophilia is detected in as many as two thirds of study cases of perinatal and neonatal stroke
Type of thrombophilia | ||||||||
---|---|---|---|---|---|---|---|---|
Study | Infants | Thrombophilia | FVL | APCR | ACA | AT | PC | PS |
Golomb et al31 | 22 | 14 (63%) * | 1 * | 3 * | 12 * | 0 | 0 | 0 |
Bonduel et al32 | 30 | 9 (30%) † | n/a | n/a | n/a | 2 | 1 | 2 |
deVeber et al49 | 92 | 35 (38%) ‡ | 0 | 6 | 23‡ | 10‡ | 6‡ | 3‡ |
Mercuri et al50 | 24 | 10 (42%) | 5 | n/a | n/a | 0 | 0 | 0 |
Günther et al35 | 91 | 62 (68%) | 17 | n/a | 3 | 0 | 6 | 0 |
Govaert et al51 | 40 | 3 (8%) | 3 | n/a | n/a | n/a | n/a | n/a |
* FVL, APCR, and ACA diagnoses overlapped. | ||||||||
† Three patients had anticardiolipin antibody and plasminogen deficiency. | ||||||||
‡ Of 35 children, 21 had multiple abnormalities (combined coagulation deficiencies). | ||||||||
Key: ACA, anticardiolipin antibody; APCR, activated protein C resistance; AT, antithrombin deficiency; FVL, factor V Leiden; PC, protein C deficiency; PS, protein S deficiency; n/a, not available or not studied. |
Brain injury
The brain is the largest and most vulnerable fetal organ susceptible to thrombi that are formed either in the placenta or elsewhere.16 A review of cases of cerebral palsy has revealed a pathologic finding, fetal thrombotic vasculopathy (FTV), that has been associated with brain injury.16 Arias and colleagues17 and Kraus18 have observed a correlation among cerebral palsy, a thrombophilic state, and FTV.
Furthermore, Redline found that the presence of severe fetal vascular lesions correlated highly with neurologic impairment and cerebral palsy.19
What is the take-home message?
Regrettably for patients and their offspring, evidence about the relationship between thrombophilia and an adverse neurologic outcome is insufficiently strong to offer much in the way of definitive recommendations for the obstetrician.
We can, however, make some tentative recommendations on management:
Consider screening. When cerebral palsy occurs in association with perinatal stroke, fetal and maternal screening for thrombophilia can be performed.34 The recommended thrombophilia panel comprises tests for:
- factor V Leiden
- prothrombin G20210
- anticardiolipin antibody
- MTHFR mutation.10
Family screening has also been suggested in cases of 1) multiple prothrombotic risk factors in an affected newborn and 2) a positive family history.9
The cost-effectiveness of screening for thrombophilia has not been evaluated in prospective studies, because the positive predictive value of such screening is extremely low.
Consider offering prophylaxis, with cautions. A mother whose baby has been given a diagnosis of thrombophilia and fetal or neonatal stroke can be offered thromboprophylaxis (heparin and aspirin) during any subsequent pregnancy. The usefulness of this intervention has not been well studied and is based solely on expert opinion, however, so it is imperative to counsel patients on the risks and benefits of prophylactic therapy beforehand.