Saline lock, also known as heparin lock, refers to the medication that keeps intravenous catheters open and flowing freely. WebMD explains that saline lock helps to keep blood flowing smoothly and prevents it from clotting in the catheter by making anti-clotting protein in the body work better. However, doctors do not use this anticoagulant to treat or prevent blood clots in the body or on infants.
Lamaze-certified childbirth educator, Robin Elise Weiss, explains that a saline lock provides vein access for low-risk pregnancies at a hospital. The saline lock allows immediate access to a vein when delivering intravenous pain medications, such as Stadol or Demerol, in the event that the pregnant woman requests epidural anesthesia, requires a Cesarean section or has a postpartum hemorrhage.
WebMD further states that heparin comes in many strengths and may cause side effects, including prolonged bleeding from cuts or gums, persistent nosebleeds, unusually heavy or prolonged menstrual periods, unusual or easy bruising, dark urine, black stools, severe headache, unusual dizziness, and unusual pain, swelling or discomfort. Other possible side effects include pain or loss of feeling in the arms or legs, change in the color of the arms or legs, chest pain, trouble breathing, confusion, weakness on one side of the body, slurred speech and vision changes.