Fetal scalp blood testing is a technique used in
obstetrics
Obstetrics is the field of study concentrated on pregnancy, childbirth and the postpartum period. As a medical specialty, obstetrics is combined with gynecology under the discipline known as obstetrics and gynecology (OB/GYN), which is a sur ...
during
labor
Labour or labor may refer to:
* Childbirth, the delivery of a baby
* Labour (human activity), or work
** Manual labour, physical work
** Wage labour, a socioeconomic relationship between a worker and an employer
** Organized labour and the la ...
to confirm whether fetal oxygenation is sufficient.
The procedure can be performed by creating a shallow cut by a
transvaginally inserted
blood lancet, followed by applying a thin pipe to the site that samples blood by
capillary action
Capillary action (sometimes called capillarity, capillary motion, capillary rise, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of, or even in opposition to, any external forces li ...
.
Two constituents that are commonly tested by this method are
pH and
lactate
Lactate may refer to:
* Lactation, the secretion of milk from the mammary glands
* Lactate, the conjugate base of lactic acid
Lactic acid is an organic acid. It has a molecular formula . It is white in the solid state and it is miscible with w ...
, both being indicators of
acid base homeostasis. A low pH and high level of lactate indicate that there is
acidosis
Acidosis is a process causing increased acidity in the blood and other body tissues (i.e., an increase in hydrogen ion concentration). If not further qualified, it usually refers to acidity of the blood plasma.
The term ''acidemia'' describe ...
, which in turn is associated with
hypoxia.
Scalp pH and lactate appear to have the same
sensitivity in predicting umbilical artery acidemia.
Analysis of pH requires a relatively large amount of blood (30–50 μl), and sampling failure rates of 11–20% have been reported.
[ Analysis of lactate only requires 5 μl of blood.][
]
See also
* Fetal scalp stimulation test
References
Tests during pregnancy
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