Fetal scalp blood testing is a technique used in
obstetrics 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
A blood lancet, or simply lancet, is a small medical implement used for capillary blood sampling. A blood lancet, sometimes called a lance, is similar to a scalpel style lancet, but with a double-edged blade and a pointed end. It can even be a ...
, 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, both being indicators of
acid base homeostasis
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...
. 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'' describes ...
, 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
Fetal scalp stimulation test is a diagnostic test used to detect fetal metabolic acidemia. It can be used as a non-invasive alternative to fetal scalp blood testing.
Procedure
A firm digital pressure on head or a gentle pinch of fetal head
The ...
References
Tests during pregnancy
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