Lamiinaria tents are made of the stems of the algae Laminaria digitate and Laminaria Japonica. Laminaria is seaweed that is mostly grown and cultivated in Korea, China, and Japan. It is written about in the Chinese literature that dates back over 1000 years. For the past 100 years Laminaria have been used in the U.S.. The standard stick is approximately 6 to 7 mm in length and 2 to 3 mm in diameter. The Laminaria sticks are individually packaged and sterilized using gamma-irradiation.

Laminaria use in Early Second Trimester Abortions (12.5 to 17 weeks) is associated with reduced maternal morbidity (complications to the mother) and mortality). Laminaria work by its hydroscopic (swelling) action by removing water from the cervix (lower womb). The Laminaria tent is associated with the synthesis and release of prostaglandins. This causes local changes to occur in the cervix that leads to the maturation (softening and dilation) of the cervix which allows for easier use of surgical dilators or shortens the induction (uterine contractions to delivery of gestational tissue) interval with the use of prostaglandins, and also reduces the amount of prostaglandins that are needed to terminate a pregnancy which in return reduces the side effects associated with the use of using prostaglandins.

Attempting to dilate the cervix with cervical dilators (serial enlarging rods) in patients in early second trimester abortions without cervical preparation or maturation (softening and opening of cervix) can lead to an increased incidence of cervical tears, cervical lacerations, damage to the cervical musculature, cervical incompetence where early miscarriages occur due to the cervix not able to hold a pregnancy, uterine (womb)perforation (hole in uterus), bowel injury, retained products of conception (pregnancy tissue remains in uterus), bleeding, or maternal death. The complication rate is reduced by 20 to 40% by using Laminaria. Laminaria tents are inserted into the patients cervix. Generally 1 to 6 are placed in patients that are in their early second trimester of pregnancy.

The Laminaria remain in the cervix from 3 to 24 hours. The earlier the length of pregnancy, the less time that is generally needed for the cervical maturation process to take place. Some patients remain in the office for the three or four hours before the surgical procedure is performed. Other patients are sent home to return the following day for the surgical procedure is to be performed. The opening and softening of the cervix can be so adequate, that serial dilators are not necessary to carry out the surgical procedure. It can be done with placement of a adequate size suction currette and when the procedure is performed under ultrasound guidance, it leads to minimal morbidity for the patient.

The complications that can occur with Laminaria tents include difficulty with removal of the tent, displacement of the tent into the vagina or the uterus, impactment (stuck inside) of the Laminaria in the cervix, breaking off of the tip ends. These complications are rare if the Laminaria are carefully placed straight inside the cervix. Other complications include cramps on insertion, and menstruation-like symptoms in approximately 8% of patients. There are a few reported cases of anaphylactic reactions after insertion, and infection. Laminaria are recommended for reduced incidence of trauma to the cervix, reduction in the time it takes to perform the surgical abortion procedure, reduction in blood loss, uterine perforation or cervical laceration when performing early second trimester abortion procedures.